Microsoft Warns Of Zero-Day Vulnerability In Internet Explorer

Microsoft has discovered a zero-day vulnerability in most versions of Internet Explorer that already has enabled some attackers to execute code remotely on victim PCs, even without action by the end user. In a security advisory issued over the weekend, Microsoft reported that it "is aware of limited, targeted attacks that attempt to exploit a vulnerability" in IE 6, 7, 8, 9, 10, and 11. The vulnerability, which takes advantage of the way IE accesses an object in memory that has been deleted or has not been properly allocated, makes it possible for attackers to do remote code execution on a targeted machine, the advisory says.

"An attacker could host a specially crafted website that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the website," Microsoft says. "An attacker who successfully exploited this vulnerability could gain the same user rights as the current user."

Remote code execution means that attackers could distribute malware via a drive-by installation, "where simply looking at booby-trapped content such as a Web page or image file can trick IE into launching executable code sent from outside your network," notes Paul Ducklin, a researcher at security firm Sophos, in a blog posted Sunday. "There won't be any obvious warning signs, or 'Danger, Will Robinson' dialog boxes."

Using such an exploit, "a crook may be able to sneak malware onto your computer even if you don't take any obvious risks such as opening a suspicious attachment or agreeing to download a dubious-sounding file," he observes.

There is no patch yet for the vulnerability, but users can reduce the risk of exploit by turning off Active Scripting, disabling the Adobe Flash files that might be used as a lever for an attack, Ducklin says.

"The zero-day identified over this weekend requires an older vulnerability, identified in 2010, to be exploited in tandem in order for the attack to be effective," says Brandon Hoffman, vice president of cyber security at RedSeal, a security firm. "Organizations that have identified and prioritized this older vulnerability and patched it should be significantly more protected. Another key component is the ability of an attacker to move laterally across the network, imitating the user of the system compromised. Any organization that has properly segmented their network will be at low risk to sensitive data being accessed."

Lucas Zaichkowsky, enterprise defense architect AccessData, says the early exploit has been attributed to a group of attackers in China. "Because the exploit is only known to a Chinese group targeting specific organizations, Microsoft will likely wait until the next Patch Tuesday to make a patch available to the general public," he says.

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I couldn't help but think that the sriousness of this vulnerability and the existing threat landscape would prompt Microsoft to patch the flaw for XP as well. Sure enough, there is an out of band patch for all versions including XP.

I have also seen that a vast majority of instances where this vulnerability is prevalent deals with VGX.dll. This is based on a deprecated markup language and most likely is should no longer be used at your enterprise unless you have legacy systems running.

The resolution for this involves unregistering of the DLL which can be accomplished easily by using the command-line. Also, make sure you do this is a test environment first. It would be very detrimental if your enteprise did run an application that leverage VGX.dll.

EMET 4.1 to be specific. Also if you are running Enhanced Protection Mode for versions 10 and 11 for IE this will also help mitigation of this vulnerability.

Protected mode which is is EPM's predecessor from IE7 has the ability to leverage XSS filter but this only alleviates the stress for Web Vulnerability exploits and not Browser Exploits. The EPM has functionality to protect against memory vulnerabilities leveraged from your browser as well as XSS. For these two reasons Enhanced Protection Mode should be enabled on all machines running IE 10/11.

So, this exploit does not escalate to System privileges? I don't see this being much of a concern if successfully executed from a Standard account. If for some problematic reason with client software they MUST be an Administrator, their Internet Explorer could always be launched using DropMyRights.

Published: 2015-03-03Off-by-one error in the ecryptfs_decode_from_filename function in fs/ecryptfs/crypto.c in the eCryptfs subsystem in the Linux kernel before 3.18.2 allows local users to cause a denial of service (buffer overflow and system crash) or possibly gain privileges via a crafted filename.

Published: 2015-03-03** REJECT ** DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: none. Reason: This candidate was withdrawn by its CNA. Further investigation showed that it was not a security issue in customer-controlled software. Notes: none.

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